title: The asymmetric structure of an icosahedral virus bound to its receptor suggests a mechanism for genome release.
abstract: Simple, spherical RNA viruses have well-understood, symmetric protein capsids, but little structural information is available for their asymmetric components, such as minor proteins and their genomes, which are vital for infection. Here, we report an asymmetric structure of bacteriophage MS2, attached to its receptor, the F-pilus. Cryo-electron tomography and subtomographic averaging of such complexes result in a structure containing clear density for the packaged genome, implying that the conformation of the genome is the same in each virus particle. The data also suggest that the single-copy viral maturation protein breaks the symmetry of the capsid, occupying a position that would be filled by a coat protein dimer in an icosahedral shell. This capsomere can thus fulfill its known biological roles in receptor and genome binding and suggests an exit route for the genome during infection.
authors.affiliation: Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Kyle C
authors.initials: KC
authors.lastname: Dent
authors.forename: Rebecca
authors.initials: R
authors.lastname: Thompson
authors.forename: Amy M
authors.initials: AM
authors.lastname: Barker
authors.forename: Julian A
authors.initials: JA
authors.lastname: Hiscox
authors.forename: John N
authors.initials: JN
authors.lastname: Barr
authors.forename: Peter G
authors.initials: PG
authors.lastname: Stockley
authors.forename: Neil A
authors.initials: NA
authors.lastname: Ranson
mesh_terms: D002213:Capsid / Q000737:chemistry / Q000648:ultrastructure*; D036022:Capsid Proteins / Q000737:chemistry / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D055032:Electron Microscope Tomography; D004926:Escherichia coli / Q000821:virology; D010861:Fimbriae, Bacterial / Q000648:ultrastructure*; D016679:Genome, Viral; D017909:Levivirus / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure*; D008958:Models, Molecular; D053585:Virus Attachment; D053586:Virus Internalization
chemical_list: D036022:Capsid Proteins